This invention relates generally to mine roof supports, and more particularly to the installation of a yieldable mine roof support.
Mine roof supports are often required in active mines to prevent arching of the roof over time and possible collapsing of the roof. Roof supports may also be used in areas of a mine no longer being worked. The support is typically made of wood columns or cribs, or cast-in-place concrete members. However, these constructions have certain drawbacks. For example, supports constructed of precast concrete members have inherent lines of weakness between the members, thereby decreasing the overall strength of the support. While a poured concrete support overcomes this problem, special forms for the concrete must be fabricated, resulting in high installation costs. Furthermore, these supports do not allow for settling or convergence of the mine roof relative to the mine floor. It is important that the mine roof support be made from a yieldable material so that in the event of such settling or convergence, the support will yield and continue to support the roof without exhibiting failure. Other types of devices made of wood or other materials that allow for displacement between the roof and the floor commonly exhibit columnar or shear failure of the support.
There is a need therefore, for a more cost effective and efficient way to construct a permanent mine support that will last over an extended period of time.
Among the several objects of this invention may be noted the provision of a mine roof support formed from a yieldable material to permit yielding during a mine convergence, for example, while continuing to provide support to the mine roof; the provision of such a support which is highly resistant to columnar shear failure; the provision of such a support which is quick and easy to erect and which is readily adaptable to fit passageways of different heights and widths; the provision of such a support which is economical to manufacture; the provision of such a support which occupies minimal space within the mine and minimizes restriction of travel within the mine; and the provision of such a support which is durable to support a mine roof over a period of time.
A mine roof support of this invention is adapted to extend vertically in a mine passageway. In general, the mine roof support includes a containment structure having at least two telescoping containment members freely telescopically movable relative to one another and a filler material introducible into the containment structure to form a column of material extending vertically in the passageway. Each containment member defines an interior space for receiving the filler material. The material is hardenable inside the containment structure to form a yieldable column whereby in the event of a mine convergence the yieldable material yields while providing continued support and the telescoping containment members move freely relative to one another to permit such yielding without damage to the containment structure.
A method of installing a roof support of this invention in a mine passageway generally includes the steps of pumping a fluid, hardenable material into the telescoping containment members to cause the upper containment member to telescopically rise with respect to the lower containment member to form a column of material inside the containment structure, allowing the hardenable material to form a yieldable set inside the containment structure, and leaving the telescoping containment structure with the hardened material therein permanently in place while allowing for freedom of movement between the telescoping parts of the containment structure so that in the event of a mine convergence the yieldable material yields while providing continued support and the telescoping containment members of the containment structure move freely relative to one another to permit such yielding without damage to the containment structure.
Other objects and features will be in part apparent and in part pointed out hereinafter.